Method for improving the accuracy of position sensorless vector control system of synchronous reluctance motor

Abstract

The present invention discloses a method for improving the accuracy of a synchronous reluctance motor position sensorless vector control system. The method adopts a filter-free current polarity identification method and a dead zone voltage compensation method to perform dead zone compensation on a position sensorless vector control system using a square wave injection method, effectively avoiding the use of a large number of filters in traditional systems, improving the system response speed and dead zone compensation accuracy, reducing the controller computing load, and retaining the advantages of the square wave injection method position sensorless vector control method to the maximum extent. After dead zone compensation, the position observation accuracy can also be greatly improved, thereby improving the stability and dynamic response performance of the motor operation and reducing torque pulsation. Under the condition of no filter, a compensation voltage vector switching mechanism including two hysteresis angles is introduced, thereby weakening the influence of the angle fluctuation of the dead zone harmonic current on the dead zone compensation effect.

Description

Technical Field

[0001] The present invention relates to the technical field of synchronous reluctance motor control, and more specifically, to a method for improving the accuracy of a synchronous reluctance motor position sensorless vector control system. Background Art

[0002] A key step of the original filterless square wave injection method is to perform filterless signal separation by utilizing the characteristic that the high-frequency current response amplitude is equal but the polarity is opposite when the square wave signal is injected. However, in practical applications, this step will produce position observation errors due to inverter nonlinearity, sampling errors, etc. Patents and research on error analysis consider error analysis under injection frequency conditions above 10kHz, and generally only consider the influence of the distortion of the injected high-frequency voltage itself, without considering the changes in the fundamental frequency current and its harmonics (especially when the dead zone is introduced), making this method not as accurate as in theory, resulting in large errors.

[0003] In actual applications, some motors, especially SynRMs with high torque density, also have large inductance. At the same time, the accuracy of industrial current sensors is limited. When the injection frequency is too high, the current sampling accuracy will be very poor. Therefore, the injection square wave frequency is often only 2kHz or even 1kHz. At lower injection frequencies (switching frequency remains unchanged), the harmonic current caused by the dead zone effect will have a greater impact on the accuracy of position observation and system stability. However, there are few substantive research methods in the prior art on the impact of dead zone harmonic current on position observation accuracy.

[0004] In addition, most of the existing dead zone compensation methods require current polarity detection. In order to reduce the impact of high-frequency current at zero crossing, the traditional current polarity detection method must filter out the high-frequency component through a low-pass filter in the dq axis coordinate system, and accurate rotor position information is also required to calculate the spatial position of the current vector. These two characteristics are not applicable to the filter-free high-frequency square wave injection method. The reintroduction of the filter will cause additional computational load to the system, and because there will always be some angle errors in the position sensorless vector control system, the compensation effect is poor. Summary of the invention

[0005] In response to at least one defect or improvement need in the prior art, the present invention provides a method for improving the accuracy of a position sensorless vector control system of a synchronous reluctance motor, so as to solve the technical problem of how to improve the control accuracy and system stability by reducing the current harmonics and rotor position observation errors caused by the dead zone effect while maintaining a low computing load.

[0006] To achieve the above object, according to a first aspect of the present invention, a method for improving the accuracy of a synchronous reluctance motor position sensorless vector control system is provided, comprising the steps of:

[0007] The current polarity is identified by using a filter-free method, the high-frequency current component is filtered out in the observation dq axis coordinate system and converted to the αβ axis stationary coordinate system to obtain the current spatial position angle;

[0008] When identifying the current spatial position and selecting the compensation voltage vector, a hysteresis angle is set at the front position and the rear position of the compensation voltage vector switching point respectively, so as to weaken the influence of the angle fluctuation of the dead zone harmonic current on the dead zone compensation effect;

[0009] Based on the improved current spatial position angle recognition and compensation voltage vector selection by introducing the hysteresis angle, the corresponding compensation voltage vector is output, and then the compensation voltage vector is superimposed with the controller voltage command value and input into the inverter together.

[0010] Furthermore, the current is processed in the dq axis coordinate system in a filter-free manner to remove the high-frequency response current component, and its expression is:

[0011]

[0012] In the formula, i sd is the current after removing the high-frequency component of the d-axis, i sq is the current after removing the high-frequency component of the q axis, k represents the kth sampling time, k-1 represents the k-1th sampling time; then through coordinate transformation, i sd 、i sq Export α 、i β ,i α is the α-axis current component, i β is the β-axis current component.

[0013] Furthermore, the calculation formula of the current space position angle is:

[0014] θ=arctan(i α / i β )

[0015] Wherein, θ is the current spatial position angle.

[0016] Furthermore, the stator current polarity can be judged by the current spatial position angle; the magnitude of the error voltage vector is obtained through the dead zone effect of the inverter; and the direction of the error voltage vector is obtained by binary numbering the stator current polarity and converting the binary numbering result into decimal.

[0017] Furthermore, the object of compensation is the error of the sensorless vector control method caused by the dead zone effect of the inverter, and the error comes from the dead zone harmonic current with the current harmonic order of ±6.

[0018] Furthermore, the function expression of the error caused by the harmonic current of the dead zone effect and the fluctuation of the position observer input value is:

[0019]

[0020] Where 2kΔθ e is the ideal value of the position observer input value, Error is the error relative to the ideal observer input value, is the envelope of the actual value of the α-axis high-frequency response current, is the envelope of the actual value of the β-axis high-frequency response current, is the estimated electrical angle, Δθ e is the estimated angle error, i dhe (n) is the d-axis high frequency response current separation error, i qhe (n) is the q-axis high frequency response current separation error, u dh (n) is the injected high-frequency square wave voltage, and k represents the time corresponding to the kth sampling.

[0021] Furthermore, a hysteresis angle is set at the front position and the rear position of the compensation voltage vector switching point respectively, and the method for switching the compensation voltage vector is specifically as follows:

[0022] For the first switching point δ1 between the first compensation voltage vector position and the second compensation voltage vector position, when the current spatial position angle exceeds δ1+θ f When the compensation voltage vector is switched from the second compensation voltage vector position to the first compensation voltage vector position along with the rotation direction of the current vector; after switching, when the current spatial position angle fluctuates to less than δ1-θ b When θ , the compensation voltage vector switches back to the second compensation voltage vector position, otherwise it does not switch back; f is the first hysteresis angle, θ b is the second hysteresis angle.

[0023] Furthermore, the first hysteresis angle θ f =π / 60, the second hysteresis angle θ b =π / 30.

[0024] According to a second aspect of the present invention, there is provided a precision improvement device for a synchronous reluctance motor position sensorless vector control system, comprising at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit executes the steps of any one of the above methods.

[0025] According to a third aspect of the present invention, there is provided a storage medium storing a computer program executable by an access authentication device, wherein when the computer program is run on the access authentication device, the access authentication device executes the steps of any one of the above methods.

[0026] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0027] (1) The present invention adopts a filter-free current polarity identification method and a dead zone voltage compensation method to perform dead zone compensation on a position sensorless vector control system using a square wave injection method, effectively avoiding the use of a large number of filters in traditional systems, improving the system response speed and dead zone compensation accuracy, reducing the controller computing load, and at the same time retaining the advantages of the position sensorless vector control method of the square wave injection method to the maximum extent. After dead zone compensation, the position observation accuracy can also be greatly improved, thereby improving the stability and dynamic response performance of the motor operation and reducing torque pulsation.

[0028] (2) The present invention introduces a compensation voltage vector switching mechanism including two hysteresis angles without a filter, thereby weakening the influence of the current space angle fluctuation caused by the dead zone harmonic current on the dead zone compensation effect.

[0029] (3) The present invention obtains a new source of position observation error that has not been considered (i.e., the current harmonics generated by the dead zone effect) by analyzing and deriving the current harmonics generated by the dead zone effect and the sensorless vector control algorithm based on the square wave injection method, and quantifies the influence of the dead zone effect harmonic current on the position observation accuracy, which can guide the subsequent error compensation, thereby improving the control accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A flow chart of a method for improving the accuracy of a synchronous reluctance motor position sensorless vector control system provided by an embodiment of the present invention;

[0032] Figure 2 A schematic diagram of a filter-free signal observer model provided by an embodiment of the present invention;

[0033] Figure 3 A schematic diagram of the circuit structure of an inverter with a synchronous reluctance motor load provided by an embodiment of the present invention;

[0034] Figure 4 A schematic diagram for comparing an ideal switching cycle and an actual switching cycle provided by an embodiment of the present invention;

[0035] Figure 5 The spatial position distribution diagram of 6 error voltage vectors provided in the embodiment of the present invention;

[0036] Figure 6 A schematic diagram of the functional relationship between the high-frequency square wave voltage, the high-frequency response current and the fundamental current provided in an embodiment of the present invention;

[0037] Figure 7 A schematic diagram of DC and non-DC components in the dq axis voltage provided by an embodiment of the present invention;

[0038] Figure 8 A comparison chart of theoretical high-frequency signal separation values ​​and actual separation values ​​provided in an embodiment of the present invention (wherein ideal means ideal and actual means actual);

[0039] Fig. 9 A spatial position distribution diagram of six compensation voltage vectors for weakening the dead zone effect provided by an embodiment of the present invention;

[0040] Fig.10 A calculation diagram for determining the current spatial position angle in the αβ coordinate system provided by an embodiment of the present invention;

[0041] Fig.11 A diagram showing the relationship between the current spatial position and the compensation voltage vector provided by an embodiment of the present invention;

[0042] Fig.12 A schematic diagram of a hysteresis angle of a current spatial position angle provided in an embodiment of the present invention;

[0043] Fig.13 A diagram showing the relationship between the improved current spatial position and the compensation voltage vector provided by an embodiment of the present invention;

[0044] Fig.14 A schematic diagram of an overall mathematical model of a method for improving the accuracy of a position sensorless vector control system of a synchronous reluctance motor provided by an embodiment of the present invention;

[0045] Fig.15 A block diagram of an electronic device suitable for implementing the method described above provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] The terms "first", "second" or "third" etc. in the specification, claims or the above-mentioned drawings of this application are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units that are not listed, or may optionally include other steps or units inherent to these processes, methods, products or devices.

[0048] like Figure 1 As shown, in one embodiment, a method for improving the accuracy of a synchronous reluctance motor position sensorless vector control system mainly includes steps S1-S3:

[0049] S1. Use a filter-free method to identify the current polarity, filter out the high-frequency current component of the current in the observed dq axis coordinate system and convert it to the αβ axis stationary coordinate system to obtain the current spatial position angle.

[0050] S2. When identifying the current spatial position and selecting the compensation voltage vector, a hysteresis angle is set at the front position and the rear position of the compensation voltage vector switching point respectively, so as to weaken the influence of the angle fluctuation of the dead zone harmonic current on the dead zone compensation effect.

[0051] S3. Based on the improved current spatial position angle recognition and compensation voltage vector selection introduced with the hysteresis angle, the corresponding compensation voltage vector is output, and then the compensation voltage vector is superimposed with the controller voltage command value and input into the inverter together.

[0052] More specifically, the synchronous reluctance motor (Synchronous Reluctance Motor, SynRM) is a complex system. In order to facilitate theoretical analysis, it is usually assumed that the magnetic circuit is not saturated, and the iron loss and eddy current loss are zero when establishing the mathematical model. Under this premise, the voltage equation and magnetic flux equation of the SynRM in the rotor synchronous speed coordinate system (i.e., dq coordinate system) can be obtained, as shown in equations (1) and (2) respectively:

[0053]

[0054]

[0055] where u d and u q denote the d-axis voltage and q-axis voltage respectively, i d and i q Represent the d-axis current and q-axis current respectively; ω e is the rotor electrical angular velocity (in rad / s); ψ d and ψ q are the d-axis magnetic flux and the q-axis magnetic flux, R s represents the stator resistance, p represents the differential operator, L d and L q They represent the d-axis inductance and q-axis inductance respectively. Under high frequency conditions, because the injection frequency is relatively high, equation (1) can be simplified to equation (3):

[0056]

[0057] The use of filters will reduce the dynamic performance of the system, cause phase errors and occupy additional chip computing power. This is one of the main reasons why the square wave voltage injection method without filters is becoming more and more popular. When the injected high-frequency signal is a high-frequency square wave signal in the form of equation (4), transforming equation (3) from the estimation coordinate system to the αβ stationary coordinate system can obtain a high-frequency current response in the form of equation (5).

[0058]

[0059]

[0060] (4) where U inj is the amplitude of the injected signal, T(θ e ), is the coordinate system transformation matrix of the form (6), represents the estimated electrical angle, θ e Represents the electrical angle, i αh and i βh They represent the α-axis high-frequency current component and the β-axis high-frequency current component, respectively. dh and i qh They represent the d-axis high-frequency current component and the q-axis high-frequency current component, u dh and u qh They represent the d-axis high-frequency voltage component and the q-axis high-frequency voltage component respectively.

[0061]

[0062] By extracting the envelope signal of the current response, we can get the response signal containing the position information, as shown in equation (7), where Δθ e To estimate the angle error, Iαh and I βh Represent the high-frequency current envelope of the α-axis and β-axis, f h Represents the frequency of the injected square wave voltage.

[0063]

[0064] Under non-high-speed conditions, the frequency of the injected high-frequency square wave signal is usually much greater than the frequency of the base-frequency current, and the base-frequency current can be considered to be basically unchanged within a square wave cycle. The frequency of the injected signal is kept as an integer multiple of the PWM carrier signal and half of the sampling frequency (due to the accuracy limitations of industrial current sensors, if the injection frequency is too high, the response current will be too small to be easily detected, and the injection frequency will often not be equal to the carrier frequency). At the same time, the high-frequency response current is symmetrical, with equal amplitudes and opposite polarities at adjacent sampling moments. Therefore, the high-frequency response current signal can be separated by calculation without the need for a filter.

[0065] At the nth sampling moment, the high-frequency response current of the α-axis and the β-axis can be calculated by equation (8), where the k in the brackets represents the kth sampling value, k-1 represents the k-1th sampling value, and the subscript h represents the high-frequency quantity.

[0066]

[0067] The high-frequency current signal obtained by equation (8) is converted into the αβ coordinate system, and then passed through the envelope extractor to obtain I αh and I βh . It can be seen that the value of the high-frequency or base-frequency current at any sampling time can be obtained through the values ​​of two adjacent samples. The filter-free signal separation method greatly improves the response speed of the system, reduces the phase error, and can significantly improve the control performance. After obtaining equations (7) and (8), the position information is further extracted using the Romberg observer or phase-locked loop, such as Figure 2 shown.

[0068] like Figure 3 As shown in the figure, when using the inverter in practical applications, due to the limitations of the physical properties of the switching device (such as the turn-on and turn-off time, etc.), a dead zone needs to be set to avoid malfunctions and damage to the equipment. Due to the existence of the dead zone, the PWM signals driving a pair of bridge arms of the inverter will not be strictly complementary, which will cause the output voltage to be distorted and generate dead zone harmonic currents, which is one of the error sources of the position sensorless vector control system.

[0069] The distortion of dead zone voltage is analyzed through the switching characteristics of the inverter. Figure 3 Taking the inverter bridge A phase switch device (S1, S4) as an example, Figure 4In the figure, the upper half shows the PWM drive waveform under ideal conditions, while the lower half shows the PWM drive waveform after the dead zone is introduced. Under ideal conditions, the on and off of the upper and lower bridge arms are strictly complementary; but under the influence of the dead zone setting, the switch tube will be delayed for a dead zone time before it can be turned on, so there will be a period of time when both the upper and lower bridge arms are in the off state, and the current can only flow through the diode.

[0070] Using the voltage average equivalent principle, since the three-phase currents differ by 120° electrical angle, we can obtain six error voltage vectors generated in the motor windings due to the dead zone setting. Their spatial position distribution is as follows: Figure 5 shown.

[0071] The direction of the error voltage vector is determined by the stator current polarity. The current is defined as flowing into the motor winding as positive polarity, as shown in Table 1. According to the abc phase sequence, the phase current polarity is represented by the number 1, and the phase current polarity is represented by the number 0. The combined value is the corresponding error voltage vector. For example, when the a phase current is positive and the bc phase current is negative, it corresponds to 100, that is, ΔV4 (the binary representation of the stator current polarity number corresponds to the subscript number of the error voltage vector).

[0072] Phase A current Phase B current Phase C current serial number Error voltage vector + ﹣ ﹣ 100 <![CDATA[ΔV4]]> + + ﹣ 110 <![CDATA[ΔV6]]> ﹣ + ﹣ 010 <![CDATA[ΔV2]]> ﹣ + + 011 <![CDATA[ΔV3]]> ﹣ ﹣ + 001 <![CDATA[ΔV1]]> + ﹣ + 101 <![CDATA[ΔV5]]>

[0073] Table 1 Error voltage vector numbers corresponding to different current polarities

[0074] The voltage error of one phase caused by the dead zone of the switching device in one switching cycle is recorded as ΔV A , ΔV A The modulus length is calculated by formula (10).

[0075] V d =-f s (T d +T on -T off )V dc (9)

[0076] ΔV A =V d sgn(i a ) (10)

[0077] Where T d ,T on ,T off The dead time, the on time of the switch tube and the off time of the switch tube are set respectively. s is the switching frequency, V dc is the inverter power supply voltage; sgn(i a) is the sign function of the A-phase current. Its value is 1 when the current is in the reference direction, otherwise it is -1.

[0078] The dead zone error voltage is converted into the two-phase stationary coordinate system and the dq axis coordinate system, and Fourier decomposition is performed to obtain expressions (11) and (12):

[0079]

[0080]

[0081] Where U e is the dead zone error voltage, U αe and U βe are the α-axis component and β-axis component of the dead zone error voltage, respectively, U de and U qe They are the d-axis component and q-axis component of the dead zone error voltage respectively.

[0082] Mainly considering the ±6th harmonics, the expression (13) of the steady-state dead zone harmonic current in the dq axis coordinate system can be derived from equation (12).

[0083]

[0084] Among them, i de and i qe are the d-axis component and q-axis component of the dead zone error current, R s is the stator resistance.

[0085] Taking the current of any axis as an example, the schematic diagram of high-frequency square wave voltage, high-frequency response current and fundamental current is as follows: Figure 6 shown.

[0086] like Figure 7 As shown, the dq axis current components are decomposed and expressed as formula (14):

[0087]

[0088] In the formula, i df and i qf are the d-axis component and q-axis component of the DC current, respectively, i d+6 and i q+6 They are the d-axis component and q-axis component of the +6th harmonic current, i d-6 and i q-6 They are the d-axis component and q-axis component of the -6th harmonic current, i other is other current components including the dq axis ripple current caused by the controller. This application mainly considers the influence of ±6th harmonic current, so formula (14) is rewritten as formula (15):

[0089]

[0090] Where A / B and subscripts represent the amplitudes of the fundamental current and the harmonic current components of different orders of the dq axis current, respectively. The change in current in the sampling interval Δt can be expressed as the product of the derivative of each current component at time t and the sampling interval time Δt, as shown in formula (16):

[0091]

[0092] Assuming that the n-1th sampling corresponds to time t, and the nth sampling corresponds to time t+△t, equation (8) can be rewritten as equation (17):

[0093]

[0094] like Figure 8 As shown in Figure 1, after filter-free signal separation, the high-frequency signal actually sampled can be expressed by formula (18):

[0095]

[0096] Converting equation (17) to the αβ coordinate system yields equation (19) and the current expression (20) containing position information after passing through the envelope detector:

[0097]

[0098]

[0099] Through the above analysis and derivation, we can get formula (21), and the source of this part of the error caused by the dead zone harmonic current can be obtained from formula (21):

[0100]

[0101] Where 2kΔθ e is the ideal value of the position observer input value, Error is the error relative to the ideal observer input value, is the envelope of the actual value of the α-axis high-frequency response current, is the envelope of the actual value of the β-axis high-frequency response current, is the estimated electrical angle, Δθ e is the estimated angle error, i dhe (n) is the d-axis high frequency response current separation error, i qhe (n) is the q-axis high frequency response current separation error, u dh (n) is the injected high-frequency square wave voltage, and k represents the time corresponding to the kth sampling.

[0102] In order to reduce the error of the filterless square wave injection method under dead zone conditions, the system needs to be compensated for the dead zone. For the SVPWM (space vector pulse width modulation) commonly used without position sensor, vector synthesis compensation can be performed by configuring the zero vector, such as Fig. 9 According to the current polarity, a vector (i.e., a compensation voltage vector) equal in magnitude to the error voltage vector and opposite in direction is selected according to Table 2, thereby eliminating or reducing the influence of the dead zone.

[0103]

[0104] Table 2 Compensation voltage vector numbers corresponding to different current polarities

[0105] It can be seen that the compensation voltage vector number in Table 2, the error voltage vector number in Table 1, and the number of the binary representation of the current polarity are all in one-to-one correspondence.

[0106] When current detection is performed through the current spatial position angle, since the high-frequency current amplitudes at two adjacent sampling points are equal and the polarities are opposite, the low-frequency current signal is separated by calculating the two sampling values, as shown in formula (22), without the need for a filter:

[0107]

[0108] Convert the dq axis fundamental frequency current into αβ axis current, such as Fig.10 As shown, the spatial position of the current vector can be obtained using the αβ axis current.

[0109] exist Fig.10 Where θ is the current spatial position angle. The current is decomposed into the α-axis component i α With the β-axis component i β , use the inverse tangent function to obtain θ, as shown in formula (23):

[0110] θ=arctan(i α / i β ) (twenty three)

[0111] The corresponding relationship between the current spatial position angle θ and the three-phase stator current polarity is as follows: Fig.11 As shown. θ can be used to easily and accurately determine the polarity of the three-phase stator current. Similarly, 1 represents positive current polarity and 0 represents negative current polarity. Fig.11 Select the compensation voltage vector. For example, when θ is between -π / 6 and π / 6, the corresponding current polarity is +﹣﹣, the corresponding number is 100, and the binary to decimal conversion is 4, so select

[0112] In order to weaken the influence of the angle fluctuation of the dead zone harmonic current on the dead zone compensation effect without a filter, a front hysteresis angle (i.e., the "first hysteresis angle" mentioned in the claims) θ is specially set before and after the switching angle of the compensation voltage vector. f and the rear hysteresis angle (i.e., the "second hysteresis angle" mentioned in the claims) θ b , as shown in formula (24).

[0113]

[0114] like Fig.12 As shown, and Take the switching angle π / 6 as an example. After the hysteresis angle is introduced, when the current space position angle is π / 6, the compensation voltage vector Do not switch to But at π / 6+θ f The compensation voltage vector switches to After that, if the angle fluctuates to less than π / 6, it will not immediately fall back to But when the angle is less than π / 6-θ b Rollback is performed only when

[0115] Similarly, for the switching point π / 2, when the current spatial position angle exceeds π / 2+θ f When the compensation voltage vector is Switch to After switching, when the angle fluctuates to less than π / 2-θ b Back to Otherwise, no rollback.

[0116] For the switching point 5π / 6, when the current spatial position angle exceeds 5π / 6+θ f When the compensation voltage vector is Switch to After switching, when the angle fluctuates to less than 5π / 6-θ b Back to Otherwise, no rollback.

[0117] For the switching point 7π / 6, when the current spatial position angle exceeds 7π / 6+θ f When the compensation voltage vector is Switch to V1 com After switching, when the angle fluctuates to less than 7π / 6-θ b Back to Otherwise, no rollback.

[0118] For the switching point -π / 2, when the current spatial position angle exceeds -π / 2+θ f When the compensation voltage vector is V1 com Switch to After switching, when the angle fluctuates to less than -π / 2-θ b Fallback to V1 com , otherwise no rollback.

[0119] For the switching point -π / 6, when the current spatial position angle exceeds -π / 6+θ f When the compensation voltage vector is Switch to After switching, when the angle fluctuates to less than -π / 6-θ b Back to Otherwise, no rollback.

[0120] Finally, the relationship between the improved current spatial position and the compensation voltage vector can be obtained, such as Fig.13 shown.

[0121] The current polarity is determined by the current spatial position angle, and then according to Fig.13 After selecting the compensation voltage vector, V i com represents the compensation voltage vector, and the subscript i corresponds to the number of the error voltage vector, then:

[0122]

[0123] Project the compensation voltage vector onto the α-axis and β-axis respectively to obtain the α-axis component of the compensation voltage vector and the β-axis component The overall mathematical model of the two components is obtained as Fig.14 shown.

[0124] To compensate for ΔV4 For example, the two components are:

[0125]

[0126] Since SVPWM calculates the vector action time in the αβ coordinate system to determine the switching moment of the switch tube, the compensation voltage vector decomposed as shown in formula (26) is superimposed with the αβ voltage command value and then input into the SVPWM module together.

[0127]

[0128] After dead zone compensation is completed, the system's sensorless position observation accuracy will be greatly improved, and the system performance and response speed will also be greatly optimized.

[0129] Fig.15 A block diagram of an electronic device suitable for implementing the method described above according to an embodiment of the present disclosure is schematically shown. Fig.15The electronic device shown is only an example and should not bring any limitation to the functions and scope of use of the embodiments of the present disclosure.

[0130] like Fig.15 As shown, the electronic device 1000 described in this embodiment includes: a processor 1001, which can perform various appropriate actions and processes according to a program stored in a read-only memory (ROM) 1002 or a program loaded from a storage part 1008 to a random access memory (RAM) 1003. The processor 1001 may include, for example, a general-purpose microprocessor (such as a CPU), an instruction set processor and / or a related chipset and / or a special-purpose microprocessor (for example, an application-specific integrated circuit (ASIC)), etc. The processor 1001 may also include an onboard memory for caching purposes. The processor 1001 may include a single processing unit or multiple processing units for performing different actions of the method flow according to an embodiment of the present disclosure.

[0131] In RAM 1003, various programs and data required for the operation of system 1000 are stored. Processor 1001, ROM 1002 and RAM 1003 are connected to each other through bus 1004. Processor 1001 performs various operations of the method flow according to the embodiment of the present disclosure by executing the program in ROM 1002 and / or RAM 1003. It should be noted that the program can also be stored in one or more memories other than ROM 1002 and RAM 1003. Processor 1001 can also perform various operations of the method flow according to the embodiment of the present disclosure by executing the program stored in the one or more memories.

[0132] According to an embodiment of the present disclosure, the electronic device 1000 may further include an input / output (I / O) interface 1005, which is also connected to the bus 1004. The system 1000 may further include one or more of the following components connected to the I / O interface 1005: an input section 1006 including a keyboard, a mouse, etc.; an output section 1007 including a cathode ray tube (CRT), a liquid crystal display (LCD), etc., and a speaker, etc.; a storage section 1008 including a hard disk, etc.; and a communication section 1009 including a network interface card such as a LAN card, a modem, etc. The communication section 1009 performs communication processing via a network such as the Internet. A drive 1010 is also connected to the I / O interface 1005 as needed. A removable medium 1011, such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc., is installed on the drive 1010 as needed, so that a computer program read therefrom is installed into the storage section 1008 as needed.

[0133] According to the method flow of the embodiment of the present disclosure, it can be implemented as a computer software program. For example, the embodiment of the present disclosure includes a computer program product, which includes a computer program carried on a computer-readable storage medium, and the computer program contains a program code for executing the method shown in the flowchart. In such an embodiment, the computer program can be downloaded and installed from the network through the communication part 1009, and / or installed from the removable medium 1011. When the computer program is executed by the processor 1001, the above-mentioned functions defined in the system of the embodiment of the present disclosure are executed. According to the embodiment of the present disclosure, the system, equipment, device, module, unit, etc. described above can be implemented by a computer program module.

[0134] The embodiment of the present invention further provides a computer-readable storage medium, which may be included in the device / apparatus / system described in the above embodiment; or may exist independently without being assembled into the device / apparatus / system. The above computer-readable storage medium carries one or more programs, and when the above one or more programs are executed, the method according to the embodiment of the present disclosure is implemented.

[0135] According to an embodiment of the present disclosure, the computer-readable storage medium may be a non-volatile computer-readable storage medium, for example, may include but is not limited to: a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above. In an embodiment of the present disclosure, the computer-readable storage medium may be any tangible medium containing or storing a program, which may be used by or in combination with an instruction execution system, an apparatus or a device. For example, according to an embodiment of the present disclosure, the computer-readable storage medium may include one or more memories other than the ROM 1002 and / or RAM 1003 described above.

[0136] It should be noted that the functional modules in the various embodiments of the present invention can be integrated into a processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The above-mentioned integrated modules can be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product.

[0137] The flowchart or block diagram in the accompanying drawings illustrates the possible architecture, functions and operations of the system, method and computer program product according to various embodiments of the present disclosure. In this regard, each box in the flowchart or block diagram can represent a module, a program segment, or a part of a code, and the above-mentioned module, program segment, or a part of the code contains one or more executable instructions for realizing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in a different order from the order marked in the accompanying drawings. It should also be noted that each box in the block diagram or flowchart, and the combination of the boxes in the block diagram or flowchart can be implemented with a dedicated hardware-based system that performs a specified function or operation, or can be implemented with a combination of dedicated hardware and computer instructions.

[0138] Those skilled in the art will appreciate that the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, even if such combinations and / or combinations are not explicitly described in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features described in the various embodiments and / or claims of the present disclosure may be combined and / or combined in a variety of ways, and all of these combinations and / or combinations fall within the scope of the present disclosure.

[0139] Although the present disclosure has been shown and described with reference to specific exemplary embodiments of the present disclosure, it should be understood by those skilled in the art that various changes in form and details may be made to the present disclosure without departing from the spirit and scope of the present disclosure as defined by the appended claims and their equivalents. Therefore, the scope of the present disclosure should not be limited to the above-mentioned embodiments, but should be determined not only by the appended claims, but also by the equivalents of the appended claims.

Claims

1. A method for improving the accuracy of a synchronous reluctance motor position sensorless vector control system, characterized in that: Includes steps: The current polarity is identified by using a filter-free method, filtering out the high-frequency current component in the observed dq axis coordinate system and converting it to the αβ axis stationary coordinate system to obtain the current spatial position angle; When identifying the current spatial position and selecting the compensation voltage vector, a hysteresis angle is set at the front position and the rear position of the compensation voltage vector switching point respectively, so as to weaken the influence of the angle fluctuation of the dead zone harmonic current on the dead zone compensation effect; Based on the improved current spatial position angle recognition and compensation voltage vector selection introduced by the hysteresis angle, a corresponding compensation voltage vector is output, and then the compensation voltage vector is superimposed with the controller voltage command value and inputted into the inverter together; The functional expression of the error caused by the harmonic current of the dead zone effect causing the fluctuation of the position observer input value is: Where 2kΔθ e is the ideal value of the position observer input value, Error is the error relative to the ideal observer input value, is the envelope of the actual value of the α-axis high-frequency response current, is the envelope of the actual value of the β-axis high-frequency response current, is the estimated electrical angle, Δθ e is the estimated angle error, i dhe (n) is the d-axis high frequency response current separation error, i qhe (n) is the q-axis high frequency response current separation error, u dh (n) is the injected high-frequency square wave voltage, and k represents the time corresponding to the kth sampling; A hysteresis angle is set at the front position and the rear position of the compensation voltage vector switching point respectively, and the method for switching the compensation voltage vector is specifically as follows: For the first switching point δ1 between the first compensation voltage vector position and the second compensation voltage vector position, when the current spatial position angle exceeds δ1+θ f When the compensation voltage vector is switched from the second compensation voltage vector position to the first compensation voltage vector position along with the rotation direction of the current vector; after switching, when the current spatial position angle fluctuates to less than δ1-θ b When θ , the compensation voltage vector switches back to the second compensation voltage vector position, otherwise it does not switch back; f is the first hysteresis angle, θ b is the second hysteresis angle.

2. The accuracy improvement method according to claim 1, characterized in that: The current is processed in the dq axis coordinate system by a filter-free method to remove the high-frequency response current component. The expression is: In the formula, i sd is the current after removing the high-frequency component of the d-axis, i sq is the current after removing the high-frequency component of the q axis, k represents the kth sampling time, k-1 represents the k-1th sampling time; then through coordinate transformation, i sd 、i sq Export α 、i β ,i α is the α-axis current component, i β is the β-axis current component.

3. The accuracy improvement method according to claim 2, characterized in that: The calculation formula of the current space position angle is: θ=arctan(i α / i β ) Wherein, θ is the current spatial position angle, i α is the α-axis current component, i β is the β-axis current component.

4. The accuracy improvement method according to claim 3, characterized in that: The filter-free method comprises: The polarity of the stator current can be determined by the current spatial position angle; the magnitude of the error voltage vector is obtained by the dead zone effect of the inverter; The direction of the error voltage vector is obtained by binary numbering the stator current polarity and converting the binary numbering result into a decimal system.

5. The accuracy improvement method according to claim 4, characterized in that: The object of compensation is the error of the sensorless vector control method caused by the dead zone effect of the inverter, and the error comes from the dead zone harmonic current with the current harmonic order of ±6.

6. The accuracy improvement method according to claim 1, characterized in that: The first hysteresis angle θ f =π / 60, the second hysteresis angle θ b =π / 30.

7. A precision improvement device for a synchronous reluctance motor position sensorless vector control system, characterized in that: The method comprises at least one processing unit and at least one storage unit, wherein the storage unit stores a computer program, and when the computer program is executed by the processing unit, the processing unit executes the steps of the method according to any one of claims 1 to 6.

8. A storage medium, characterized in that: It stores a computer program executable by an access authentication device. When the computer program runs on the access authentication device, the access authentication device executes the steps of the method according to any one of claims 1 to 6.

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